China has begun construction of what is set to become the world’s largest hydropower dam in Yarlung Tsangpo Canyon located in the Tibetan Plateau.
The project has sparked concerns in downstream neighbours India and Bangladesh about the hazards of flooding, water scarcity and environmental degradation.
What’s new here
On July 19, Chinese Premier Li Qiang presided over a high-profile ceremony marking the official start of construction of the Motuo Hydropower Station—a massive $167 billion project on the Yarlung Tsangpo River.
Once completed, the dam is expected to generate three times the electricity of the Three Gorges Dam, making it the largest of its kind in the world.
A civil infrastructure of this size has never been attempted. Especially in a remote mountainous region, which sits right on top of an active seismic belt.
The Yarlung Tsangpo River transforms into the Brahmaputra as it flows downstream into northeast India’s Arunachal Pradesh and Assam states, before entering Bangladesh, where it is known as the Jamuna.
Why is it significant
While Beijing touts the project as a green energy breakthrough, authorities in India’s Arunachal Pradesh and Assam states are raising alarm over potential catastrophic effects downstream.
Arunachal’s Chief Minister Pema Khandu warned that the dam could lead to the drying up of the Siang and Brahmaputra rivers, or worse, function as a "water bomb" if China were to release water suddenly.
Similar concerns have also been expressed by Bangladeshi officials, who earlier in February this year sent a formal request to Beijing for more information on the project’s environmental impact assessment and feasibility study.
The Brahmaputra basin—stretching across India’s Arunachal Pradesh and Assam, and into Bangladesh—is one of the most flood-prone regions in the world, with seasonal deluges causing widespread devastation and thousands of deaths nearly every year.
In Assam, the Brahmaputra River is not just a lifeline but the primary source of irrigation, sustaining the state’s agrarian economy. Fears that China’s newly launched mega-dam upstream could alter the natural flow or trigger sudden water discharges have intensified concerns about the impact on the region.
Further fuelling concerns are environmental and seismic risks. The Yarlung Tsangpo Canyon is located in a high-altitude, earthquake-prone zone, raising fears about the potential for dam collapse or structural failure.
It’s interesting to note that the Indian and Bangladeshi governments have not yet officially commented on the project since work started on it.
Brief backgrounder
China hasn’t officially shared details about the design. It’s unclear if this would be a massive run-of-the-river project that involves multiple small dams and power plants or if long tunnels would be dug through the Namcha Barwa mountain to force water from higher to lower regions to generate electricity.
Yarlung Tsangpo flows through what is said to be the world’s deepest and longest land canyon. The project will be built in a region where the river falls 2,000 meters within a short stretch of 50 kilometres, making it an ideal site for power production.
Beijing hasn’t indicated that it wants to use the project for agricultural purposes. This point is important. Generally, lower riparian countries fear that water will be blocked, badly affecting the farm output.
While the Yarlung Tsangpo originates in China, most of the water it eventually discharges—as it becomes the Brahmaputra downstream—is contributed by catchment areas within India.
Research shows that while nearly 50 percent of the Yarlung Tsangpo-Brahmaputra River basin lies within Chinese territory, it contributes only a fraction of the river’s total discharge.
According to the UN Food and Agriculture Organization (FAO) report, China accounts for about 30 percent of the Brahmaputra’s flow, though other studies suggest the figure could be as low as seven percent.
What happens next
In response to the perceived threat of the new Chinese mega-dam, India is moving to fast-track the construction of its own hydropower dam on the river on its side. It wants to use it as a buffer against sudden water discharges from China.
In a recent meeting, Indian External Affairs Minister S Jaishankar asked his Chinese counterpart for cooperation on trans-border rivers.
China and India don’t have a formal water treaty that allows close cooperation on how to use shared rivers.
Trust between the two of the world’s most populous countries remains low, especially after the 2020 deadly military clash between Indian and Chinese forces over the disputed Himalayan border in Ladakh.
While recent high-level talks between the two nations have indicated a desire to “gradually improve relations”, water security is now emerging as a long-term flashpoint in their bilateral ties.
